List of astronomical interferometers at visible and infrared wavelengths

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Current performance of ground-based interferometers[edit]

Here is a list of currently existing astronomical optical interferometers (i.e. operating from visible to mid-infrared wavelengths), and some parameters describing their performance.

Columns 2-5 determine the range of targets that can be observed and the range of science which can be done. Higher limiting magnitude means that the array can observe fainter sources (and the most interesting sources are often very faint). The limiting magnitude is determined by the atmospheric seeing, the diameters of the telescopes and the light lost in the system. A larger range of baselines means that a wider variety of science can be done and on a wider range of sources.

Columns 6-10 indicate the approximate quality and total amount of science data the array is expected to obtain. This is per year, to account for the average number of cloud-free nights on which each array is operated.

Current Performance of Existing Astronomical Interferometers
Interferometer and observing mode Waveband Limiting magnitude Minimum baseline (m)
(un-projected)
Maximum baseline (m) Approx. no. visibility measurements per year
(measurements per night x nights used per year)
Max ratio of no. phase / no. amplitude measurements
(measure of imaging performance, 0 = none)
Accuracy of amplitude2 measurements Accuracy of phase measurements
(milli-radians)
Number of spectral channels
(max in use simultaneously)
Comments
CHARA Array[1] V, R, I, J, H, K 8 34 330 7500 0.7 1% 10 30000 30000 in the visible band; maximum baseline 330-m
COAST visible R, I 7 4 60 2000 0.5 4% 10 4? 300 cloudy nights per year, maximum baseline 100-m
COAST infrared J, H 3 4 60 100 0.5 20% 10 1 300 cloudy nights per year, maximum baseline 100-m
GI2T visible R, I 5 10 65 2000 0 10% - 400? CLOSED in 2006
IOTA J, H, K 7 6 30 10000 0.3 2% 10 1? Integrated optics beam combiner. CLOSED.
ISI N 0 10 50 5000 0.3 1% 1 1000 Maximum baseline 70-m
Keck Interferometer H, K, L, N 10.3 85 85 1000 0 4% 1 330 Nulling Key Science Underway - No imaging on a single baseline instrument; maximum baseline 11-m. CLOSED.
Keck Aperture Masking J, H, K, L 2 0.5 9 20000 0.9 20% 10 1 CLOSED.
MIRA 1.2 R, I 3 30 30 500 0 10% - 1 Mid-Infrared
Navy Precision Optical Interferometer(NPOI) visible V, R, I 5 5 300 50000 0.7 4% 10 16 at NOFS; siderstats operational 4 x 1.8m added apertures in FY13. World's largest optical baseline-437m, 6-phased
Palomar Testbed Interferometer[2] J,H,K 7 86 110 50000 0 2% 0.1 5,10 "dual-star" capable , No imaging on a single baseline instrument. CLOSED 2009.
SUSI B, V, R, I 5 5 640 5000 0 4% 10 21 No imaging on a single baseline instrument; Maximum baseline 160m
VLTI
+UTs AMBER
J, H, K simultaneously 7 46 130 400 0.3 1% 10 2000 Used for a few weeks per year. Longest overall VLTI Baseline 130m
VLTI
+ATs AMBER
J, H, K simultaneously 4 46 130 400 0.3 1% 10 2000 Longest overall VLTI Baseline 130m
VLTI
+UTs VINCI
K 11 46 130 400 0 >1% - 1 Integrated optics beam combiner. Longest overall VLTI Baseline 130m
VLTI
+ATs VINCI
K Never checked 12 200 400 0 >1% - 1 Longest overall VLTI Baseline 130m
VLTI
+UTs MIDI
N 4.5 46 130 200 0 10% - 250 Used for a few weeks per year. Longest overall VLTI Baseline 130m
VLTI
+ATs MIDI
N 4.5  ? 200 200 0 10% - 250 VLTI inldes World's largest unfilled apertures (siderostats, 1.8-m, 8-m). Longest overall VLTI Baseline 130m

New interferometers and improvements to existing interferometers[edit]

Expected Future Performance of Astronomical Interferometers
Interferometer and observing mode Waveband Limiting magnitude Minimum baseline (m)
(un-projected)
Maximum baseline (m) Approx. no. visibility measurements per year
(measurements per night x nights used per year)
Max ratio of no. phase / no. amplitude measurements
(measure of imaging performance, 0 = none)
Accuracy of amplitude2 measurements Accuracy of phase measurements
(milli-radians)
Number of spectral channels
(max in use simultaneously)
Comments
LBTI
(near infrared)
J, H, K >20 0 22 10000000 1 30% 100 100? 2006?
MRO R, I, J, H, K 14 7 400 100000 0.6 1% 10 1000? Under Construction
VLTI
(near infrared using 4 ATs and PRIMA)
J, H, K 12 8 200 10000 1 1% 0.1 4000? Operating every night 2008?
VLTI
(near infrared using 3 UTs and PRIMA)
J, H, K 14 46 130 500 1 1% 0.3 4000? 2008?

See also[edit]

References[edit]

  1. ^ T.A. ten Brummelaar et al. (2005). "First Results from the CHARA Array. II. A Description of the Instrument". Astrophysical Journal 628 (1): 453. arXiv:astro-ph/0504082. Bibcode:2005ApJ...628..453T. doi:10.1086/430729. 
  2. ^ M.M. Colavita et al. (1999). "The Palomar Testbed Interferometer". Astrophysical Journal 510 (1): 505. arXiv:astro-ph/9810262. Bibcode:1999ApJ...510..505C. doi:10.1086/306579. 

Further reading[edit]